[RFC PATCH 03/22] x86/fpu/xstate: Modify address finder prototypes to access all the possible areas

From: Chang S. Bae
Date: Thu Oct 01 2020 - 16:44:14 EST

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The xstate infrastructure is not flexible to support dynamic areas in
task->fpu. Change the prototype of some address finding functions to access
task->fpu directly. Make changes for both outer and inner helpers:
get_xsave_addr() and __raw_xsave_addr().

No functional change.

Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
Reviewed-by: Len Brown <len.brown@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
---
arch/x86/include/asm/fpu/internal.h | 2 +-
arch/x86/include/asm/fpu/xstate.h | 2 +-
arch/x86/include/asm/pgtable.h | 2 +-
arch/x86/kernel/cpu/common.c | 2 +-
arch/x86/kernel/fpu/xstate.c | 43 ++++++++++++++++++++---------
arch/x86/kvm/x86.c | 26 +++++++++++------
arch/x86/mm/pkeys.c | 2 +-
7 files changed, 52 insertions(+), 27 deletions(-)

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index c404fedf1a75..baca80e877a6 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -578,7 +578,7 @@ static inline void switch_fpu_finish(struct fpu *new_fpu)
* return to userland e.g. for a copy_to_user() operation.
*/
if (current->mm) {
- pk = get_xsave_addr(&new_fpu->state.xsave, XFEATURE_PKRU);
+ pk = get_xsave_addr(new_fpu, XFEATURE_PKRU);
if (pk)
pkru_val = pk->pkru;
}
diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index a315b055212f..3fbf45727ad6 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -100,7 +100,7 @@ extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
extern void __init update_regset_xstate_info(unsigned int size,
u64 xstate_mask);

-void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr);
+void *get_xsave_addr(struct fpu *fpu, int xfeature_nr);
const void *get_xsave_field_ptr(int xfeature_nr);
int using_compacted_format(void);
int xfeature_size(int xfeature_nr);
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index b836138ce852..e24a8fb8f479 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -142,7 +142,7 @@ static inline void write_pkru(u32 pkru)
if (!boot_cpu_has(X86_FEATURE_OSPKE))
return;

- pk = get_xsave_addr(&current->thread.fpu.state.xsave, XFEATURE_PKRU);
+ pk = get_xsave_addr(&current->thread.fpu, XFEATURE_PKRU);

/*
* The PKRU value in xstate needs to be in sync with the value that is
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index d0363e15ec2e..183ee7f77065 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -478,7 +478,7 @@ static __always_inline void setup_pku(struct cpuinfo_x86 *c)
return;

cr4_set_bits(X86_CR4_PKE);
- pk = get_xsave_addr(&init_fpstate.xsave, XFEATURE_PKRU);
+ pk = get_xsave_addr(NULL, XFEATURE_PKRU);
if (pk)
pk->pkru = init_pkru_value;
/*
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index e3a9bddc39d9..bab22766b79b 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -891,15 +891,23 @@ void fpu__resume_cpu(void)
* buffer the state is. Callers should ensure that the buffer
* is valid.
*/
-static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
+static void *__raw_xsave_addr(struct fpu *fpu, int xfeature_nr)
{
+ void *xsave;
+
if (!xfeature_enabled(xfeature_nr)) {
WARN_ON_FPU(1);
return NULL;
}

- return (void *)xsave + xstate_comp_offsets[xfeature_nr];
+ if (fpu)
+ xsave = &fpu->state.xsave;
+ else
+ xsave = &init_fpstate.xsave;
+
+ return xsave + xstate_comp_offsets[xfeature_nr];
}
+
/*
* Given the xsave area and a state inside, this function returns the
* address of the state.
@@ -911,15 +919,18 @@ static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
* this will return NULL.
*
* Inputs:
- * xstate: the thread's storage area for all FPU data
+ * fpu: the thread's FPU data to access all the FPU state storages.
+ (If a null pointer is given, assume the init_fpstate)
* xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP,
* XFEATURE_SSE, etc...)
* Output:
* address of the state in the xsave area, or NULL if the
* field is not present in the xsave buffer.
*/
-void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
+void *get_xsave_addr(struct fpu *fpu, int xfeature_nr)
{
+ struct xregs_state *xsave;
+
/*
* Do we even *have* xsave state?
*/
@@ -932,6 +943,12 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
*/
WARN_ONCE(!(xfeatures_mask_all & BIT_ULL(xfeature_nr)),
"get of unsupported state");
+
+ if (fpu)
+ xsave = &fpu->state.xsave;
+ else
+ xsave = &init_fpstate.xsave;
+
/*
* This assumes the last 'xsave*' instruction to
* have requested that 'xfeature_nr' be saved.
@@ -946,7 +963,7 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
if (!(xsave->header.xfeatures & BIT_ULL(xfeature_nr)))
return NULL;

- return __raw_xsave_addr(xsave, xfeature_nr);
+ return __raw_xsave_addr(fpu, xfeature_nr);
}
EXPORT_SYMBOL_GPL(get_xsave_addr);

@@ -977,7 +994,7 @@ const void *get_xsave_field_ptr(int xfeature_nr)
*/
fpu__save(fpu);

- return get_xsave_addr(&fpu->state.xsave, xfeature_nr);
+ return get_xsave_addr(fpu, xfeature_nr);
}

#ifdef CONFIG_ARCH_HAS_PKEYS
@@ -1112,7 +1129,7 @@ void copy_xstate_to_kernel(struct membuf to, struct fpu *fpu)
* Copy only in-use xstates:
*/
if ((header.xfeatures >> i) & 1) {
- void *src = __raw_xsave_addr(xsave, i);
+ void *src = __raw_xsave_addr(fpu, i);

copy_part(&to, &last, xstate_offsets[i],
xstate_sizes[i], src);
@@ -1141,13 +1158,11 @@ int copy_kernel_to_xstate(struct fpu *fpu, const void *kbuf)
if (validate_user_xstate_header(&hdr))
return -EINVAL;

- xsave = &fpu->state.xsave;
-
for (i = 0; i < XFEATURE_MAX; i++) {
u64 mask = ((u64)1 << i);

if (hdr.xfeatures & mask) {
- void *dst = __raw_xsave_addr(xsave, i);
+ void *dst = __raw_xsave_addr(fpu, i);

offset = xstate_offsets[i];
size = xstate_sizes[i];
@@ -1156,6 +1171,8 @@ int copy_kernel_to_xstate(struct fpu *fpu, const void *kbuf)
}
}

+ xsave = &fpu->state.xsave;
+
if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
offset = offsetof(struct fxregs_state, mxcsr);
size = MXCSR_AND_FLAGS_SIZE;
@@ -1198,13 +1215,11 @@ int copy_user_to_xstate(struct fpu *fpu, const void __user *ubuf)
if (validate_user_xstate_header(&hdr))
return -EINVAL;

- xsave = &fpu->state.xsave;
-
for (i = 0; i < XFEATURE_MAX; i++) {
u64 mask = ((u64)1 << i);

if (hdr.xfeatures & mask) {
- void *dst = __raw_xsave_addr(xsave, i);
+ void *dst = __raw_xsave_addr(fpu, i);

offset = xstate_offsets[i];
size = xstate_sizes[i];
@@ -1214,6 +1229,8 @@ int copy_user_to_xstate(struct fpu *fpu, const void __user *ubuf)
}
}

+ xsave = &fpu->state.xsave;
+
if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
offset = offsetof(struct fxregs_state, mxcsr);
size = MXCSR_AND_FLAGS_SIZE;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9da8cb4b8589..c4b8d3705625 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4182,10 +4182,15 @@ static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu,

static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)
{
- struct xregs_state *xsave = &vcpu->arch.guest_fpu->state.xsave;
- u64 xstate_bv = xsave->header.xfeatures;
+ struct xregs_state *xsave;
+ struct fpu *guest_fpu;
+ u64 xstate_bv;
u64 valid;

+ guest_fpu = vcpu->arch.guest_fpu;
+ xsave = &guest_fpu->state.xsave;
+ xstate_bv = xsave->header.xfeatures;
+
/*
* Copy legacy XSAVE area, to avoid complications with CPUID
* leaves 0 and 1 in the loop below.
@@ -4204,7 +4209,7 @@ static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)
while (valid) {
u64 xfeature_mask = valid & -valid;
int xfeature_nr = fls64(xfeature_mask) - 1;
- void *src = get_xsave_addr(xsave, xfeature_nr);
+ void *src = get_xsave_addr(guest_fpu, xfeature_nr);

if (src) {
u32 size, offset, ecx, edx;
@@ -4224,10 +4229,14 @@ static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)

static void load_xsave(struct kvm_vcpu *vcpu, u8 *src)
{
- struct xregs_state *xsave = &vcpu->arch.guest_fpu->state.xsave;
u64 xstate_bv = *(u64 *)(src + XSAVE_HDR_OFFSET);
+ struct xregs_state *xsave;
+ struct fpu *guest_fpu;
u64 valid;

+ guest_fpu = vcpu->arch.guest_fpu;
+ xsave = &guest_fpu->state.xsave;
+
/*
* Copy legacy XSAVE area, to avoid complications with CPUID
* leaves 0 and 1 in the loop below.
@@ -4247,7 +4256,7 @@ static void load_xsave(struct kvm_vcpu *vcpu, u8 *src)
while (valid) {
u64 xfeature_mask = valid & -valid;
int xfeature_nr = fls64(xfeature_mask) - 1;
- void *dest = get_xsave_addr(xsave, xfeature_nr);
+ void *dest = get_xsave_addr(guest_fpu, xfeature_nr);

if (dest) {
u32 size, offset, ecx, edx;
@@ -9662,6 +9671,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
vcpu->arch.apf.halted = false;

if (kvm_mpx_supported()) {
+ struct fpu *guest_fpu = vcpu->arch.guest_fpu;
void *mpx_state_buffer;

/*
@@ -9670,12 +9680,10 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
*/
if (init_event)
kvm_put_guest_fpu(vcpu);
- mpx_state_buffer = get_xsave_addr(&vcpu->arch.guest_fpu->state.xsave,
- XFEATURE_BNDREGS);
+ mpx_state_buffer = get_xsave_addr(guest_fpu, XFEATURE_BNDREGS);
if (mpx_state_buffer)
memset(mpx_state_buffer, 0, sizeof(struct mpx_bndreg_state));
- mpx_state_buffer = get_xsave_addr(&vcpu->arch.guest_fpu->state.xsave,
- XFEATURE_BNDCSR);
+ mpx_state_buffer = get_xsave_addr(guest_fpu, XFEATURE_BNDCSR);
if (mpx_state_buffer)
memset(mpx_state_buffer, 0, sizeof(struct mpx_bndcsr));
if (init_event)
diff --git a/arch/x86/mm/pkeys.c b/arch/x86/mm/pkeys.c
index 8873ed1438a9..772e8bc3d49d 100644
--- a/arch/x86/mm/pkeys.c
+++ b/arch/x86/mm/pkeys.c
@@ -177,7 +177,7 @@ static ssize_t init_pkru_write_file(struct file *file,
return -EINVAL;

WRITE_ONCE(init_pkru_value, new_init_pkru);
- pk = get_xsave_addr(&init_fpstate.xsave, XFEATURE_PKRU);
+ pk = get_xsave_addr(NULL, XFEATURE_PKRU);
if (!pk)
return -EINVAL;
pk->pkru = new_init_pkru;
--
2.17.1

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Previous message: Chang S. Bae: "[RFC PATCH 11/22] x86/fpu/xstate: Update xstate area address finder for supporting dynamic user xstate"
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Next in thread: Chang S. Bae: "[RFC PATCH 01/22] x86/fpu/xstate: Modify area init helper prototypes to access all the possible areas"
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